Onshore broadband seismic exploration for geothermal targets using a multiscale shooting grid

This study emphasizes seismic acquisition and processing advances for strategic placement of geothermal doublets, in the pursuit of optimal geothermal and lithium exploration.

The primary focus lies in identifying the most permeable zones associated with fractures and faults: enhancing seismic image bandwidth to lower frequencies proves crucial, improving vertical resolution and aiding fault interpretation. A 3D seismic survey in the French part of the Upper Rhine Graben is presented, showcasing the simultaneous use of Random Sweep and broadband multiscale data. The seismic acquisition involves a Dispersed Source Array (DSA) concept, emphasizing irregular, multi-grid, dual sweep, and dispersed source arrays for efficient data collection.

Low-frequency acquisition is achieved through vibroseis. The study introduces a unique approach involving multiscale shooting grids to achieve spatial sampling intervals for low, mid, and high frequencies. The low-frequency sweeps, emitted by different vibrators during nighttime, are narrowband and strategically spaced. This approach overcomes limitations associated with broadband vibrators and enhances the clarity of basement images and deep structures. The study’s processing sequence addresses the challenges of merging different datasets, providing a consistent kinematic and processing solution. The results demonstrate a considerable improvement of the images of the targets, for land geothermal surveys in complex environments.